Apparatus for casting metallic articles



Sept 5 1955 J. B. BRENNN APPARATUS FOR CASTING METALLIC ARTICLES IN V ENTOR.

Filed May l2 APPARATUS FOR CASTING METALLIC ARTICLES Joseph B. Brennan,Cleveland, Ohio Application May 12, 1951, Serial No. 225,949

6 Claims. (Cl. 22-73) The present invention relates generally asindicated to an apparatus for casting, the present application being acontinuation-impart of my copending application Serial No. 202,707,tiled December 26, 1950.

It is one object of this invention to provide an apparatus foreconomically, rapidly, and accurately producing, either continuously orsuccessively, castings or laminated products in which the cast materialis applied to a liner or the like in the mold cavity.

Another object of this invention is to provide a casting apparatus whichinvolves relative movement of molten material supply means andmold-cavity forming means for bringing the latter into communicationwith a pool of molten material in the former while the material is underthe influence of a vacuum, whereby air and gases are withdrawn from thecavity to facilitate the flow of the molten metal thereinto.

It is another object of this invention to provide a casting apparatus inwhich the mold cavity is successively communicated with a vacuum chamberand with a molten material supply whereby the mold cavity is rstevacuated and then lled with the molten material.

Another object is to provide an apparatus for casting in which themolding material is effectively degassed and de-oxidated. n

Other objects and advantages will become apparent as the followingdescription proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various ways in which the principle of the invention may beemployed.

In said annexed drawing:

Fig. 1 is a vertical cross-sectional view of one form of apparatusconstituting the present invention;

Fig. 2 is a fragmentary vertical section similar to Fig. l exceptillustrating a modication in the mold cavity forming means;

Fig. 3 is another fragmentary vertical cross-sectional view illustratinga still further modification in the mold cavity forming means; and

Fig. 4 is a transverse cross-sectional View taken substantially alongthe line 4 4, Fig. 3.

As illustrated in Fig. 1, the apparatus comprises a receptacle 1 ofgraphite or the like heated as by means of the high frequency heatingcoils 2 therearound, said receptacle being adapted to receive therein aquantity of molten material 3 therein either supplied intermittently orat a desired uniform rate as from a spiral trough 4 leading to thereceptacle from a suitable supply source and having associated therewitha heating coil 5, or, if desired, the material 3 to be cast may besupplied to the receptacle 1 in solid form for melting in the trough orreceptacle by the heat supplied from the heating coils 2 and 5. Thechamber 6 defined above the level of the lni'ted States Patent O moltenmaterial 3 in said receptacle 1 is evacuated and maintained at a desirednegative pressure as by means of the conduit 7 which leads to a suitablevacuum source, and, if desired, means may be provided on said receptacle1 for introducing an inert atmosphere into the chamber whereby toprevent oxidation or deterioration of the molten material 3 therein. v

The chamber 6 aforesaid may be defined by bell-shaped parts 3 and 9 ofwhich the latter preferably surrounds the receptacle 1 so that theexterior of said receptacle is not exposed to the atmosphere, said parts8 and 9 being made from heat-resistant glass, aluminum oxide, siliconcarbide, or equivalent material.

The spiral trough 4 is so formed that the material llows as a thin layertherealong and as shown said trough may have projections to produce asort of weir which would expose the molding material, such as copper,for example, to the graphite of which the trough is preferably made. Byso exposing the molten material to the vacuum, degassing and deoxidationis effected very effectively. Of course, a gas permeable carbon or liketube may be substituted for the trough 4 to spread out the moldingmaterial after it is introduced into the vacuum chamber.

While the heating coils 2 and 5 are herein shown within the parts 8 and9 surrounding the receptacle 1 and trough 4, either one or both may bedisposed exteriorly of said parts 8 or 9 or located elsewhere withinsaid parts other than in surrounding relation to the receptacle and thetrough.

Extending vertically through said receptacle 1 is a guide tube 10 alsoof graphite or the like provided with cooling means 11 around the lowerend thereof, a molten material inlet passage 12 below the level of thepool 3 in the receptacle and another passage 13 therethroughcommunicating with the vacuum chamber 6. The vacuum chamber cover 8 andreceptacle 1 may be sealed to the guide tube 10 as by means of theconventional O-rings 14 and 14A or other suitable packing means and thevacuum chamber part 9 is sealed to receptacle 1 by packing means 14B.Other packing rings 14C and 14D are disposed adjacent the upper andlower ends of said guide tube 10 operative to sealingly engage the molds15 which are adapted to be moved downwardly through the guide 10, saidmolds 15 being inserted from the top and pushed downwardly tosuccessively communicate the sprues 16 thereof with the passages 13 and12 in the guide 7 whereby as each mold 15 is positioned or passed inregister with the passage 13, the mold cavity therein is evacuated andwhen each mold is in register with the passage 12, molten material willrun into the evacuated cavity and thereby completely till the same. Asthe lled molds 15 pass downwardly, the material therein is cooled andsolidified by the cooling means 11. It is to be noted that the sealingrings 15C and 14D adjacent the upper and lower ends of the guide 10serve to cause the mold sections 1S therebetween to be pressed togetheras by the differential pressure, that is, atmospheric pressure acting onthe end molds 15 and vacuum in between successive molds. Still otherpacking rings 14A and 14B aforesaid are disposed between tube 10 andreceptacle 1 and between said receptacle and the surrounding part 9. Inorder to permit use of packing rings of rubber-like material withoutmelting, the parts are cored as at 10', 10, and 10"', 8', and 1' forcirculation of coolant such as water.

The molds 15 just described may be of the type described in detail inthe aforesaid copending application and as disclosed in my Patent No.2,530,853, dated November 2l, 1950. Briey, however, the mold cavitiesmay be formed in the molds by a process similar to the well known lostwax process, that is, embedding a meltable, combustible, or volatilemodel in a body of zirconium oxide, molding plaster, core sand, moldingsand binders, carbon, or the like whereby upon disposal of the model, anaccurate mold cavity is left without any parting lines or the like.Also, if desired, only a portion of the model may be made of suchmeltable, combustible, or volatile material whereby the non-meltable,non-combustible, or non-volatile portion of the model will remain in themold body for casting of the molten material 3 thereagainst to form alaminated product.

In order to prevent exposure of the exterior surface of the upper end oftube 10 from the atmosphere and to effect a vacuum seal, a surroundingshell 17 may be provided made of a material the same or equivalent tothat of the parts 8 and 9.

If desired, a vacuum bell may be provided on the bottom and top of tube10 so that the casting could be removed while under vacuum and also sothat the investment mold could be introduced while under vacuum.

It is to be understood that the particular mold 15 herein illustrated isto be regarded as merely typical and that, for example, adjacent molds15 may define cavities therebetween with sprues and gates leading fromthe exterior of the molds to such cavities.

The modification of the invention illustrated in Fig. 2 comprisesadjacent mold sections 20 adapted to be forced through a guide 21 and tohave the molten material 22 owed into mold cavities defined between theadjacent and interfitting mold sections 20. Here again, the moldcavities successively communicate with the vacuum chamber 23 and withthe pool of molten ma- .'f

terial 22 through the passages 24 and 25 respectively, and as aforesaidany portion of the mold cavity may be lined with a material having ahigher melting point than the temperature to which the molten pool 22 isheated whereby a laminated product may be produced.

In the modification of the invention illustrated in Figs. 3 and 4 themold-cavity forming means comprises a rod-like member 30, eithercontinuous or composed of adjacent sections and preferably ofrectangular crosssection as shown and a guide 31 having sealedengagement with the rod-like member at the upper end. The guide 31 isformed with passages 32 and 33 respectively communicating the moldcavities defined between the guide 31 and the rod member 30 with thevacuum chamber 34 and with the pool of molten material 35.

ln the particular assembly shown, the guide 31 is formed with aplurality of guide ribs 36 engaging the corners of the rod-like member30 and thereby defining four strip-like cavities 37 whereby as themolten material ows into such cavities and solidilies therein as the rod30 and adjacent material pass through the cooling zone of the guide 31,there will be produced a plurality of at strips which may be removedfrom the rodlike member 30 and further processed as by rolling or othertreatment or simply coiled or otherwise bundled without such furthertreatment.

In the modification illustrated in Fig. 3 the rod-like member 3i) may beof any desired cross-section shape and if desired the molten material 35may be cast therearound as a continuous sleeve or sheath and thenstripped from the rod-like member as disclosed in my copendingapplication Serial No. 147,466, filed February 18, 1950. ln thisconnection it is to be noted further that, if desired, the cast sheathmay become a permanent part of the rod-like member 3G, thereby forming`a laminated product.

In the forms of the apparatus shown in Figs. 2 `and 3 the lower ends ofthe guides 21 and 31 will preferably be provided with packing rings 14Dsuch as illustrated in Fig. l for making sealed engagement, in Fig. 2with the exterior surfaces of the mold sections 20 and the castingsformed between adjacent sections, and in Fig. 3 with the externalsurface of the cast strips 37 or like cast parts.

With further reference to Figs. 3 and 4, while the 4 ribs 36 are shownas being part of the guide member 31 to define cavities 37 for castingstrips, it will be apparent to those skilled in the art that such ribsmay be provided by longitudinally grooving the exterior surface of therod-like member 30 while having a regular rectangular opening throughthe guide member.

In summary, it is now apparent that with the apparatuses disclosedherein it is possible to economically produce sound castings with greatrapidity and in conformance with the mold cavities by reason ofevacuation of the mold cavities to facilitate iowing of the molten metalthereinto, such evacuation withdrawing air and gases which otherwisemight be trapped in the mold cavities. While the apparatus illustratedshow special passages 13, 24, and 32 in the guide means 10, 21, and 31,respectively, for communicating the cavity with the vacuum chambers 6,23, and 34, it can be seen that by maintaining the pool of molten metalunder vacuum, the gases in the mold cavities and in the molten metalpool will bubble through the molten material to permit deoxidation andflow of the molten material thereinto by gravity. Moreover, because themolding material is caused to flow into the receptacle 1 and into thevacuum chamber 6 (or 23, or 34 as the case may be) as a thin layer, thesame is more effectively degassed and deoxidized.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

I therefore particularly point out and distinctly claim as my invention:

l. Apparatus for casting articles comprising a mold having a cavity, aguide through which said mold is adapted to be moved, said guideproviding an inlet and an outlet for the introduction of said moldthereinto and for discharge of said mold therefrom, a receptacle formolten material, a chamber, means for controlling the atmosphere in saidchamber, said chamber and receptacle each surrounding said guide betweensuch inlet and outlet thereof, said guide being formed with passagescommunicating such chamber and the molten material in said receptaclewith the mold cavity in said mold as the latter is moved through saidguide whereby the atmosphere in such cavity is first removed and thecavity is then illed with molten material from said receptacle, andmeans for solidifying the material thus filling such cavity after thelatter passes the passage which communicates with the molten material insaid receptacle and prior to discharge of said mold from the outlet ofsaid guide.

2. The apparatus according to claim l characterized further in thatadjacent mold blocks are adapted to be inserted into said guide at oneend of the latter and to be moved therethrough to communicate therespective cavities therein with the passages in said guide.

3. The apparatus according to claim l characterized further in that themold cavity is defined between said mold and guide whereby the cavity isevacuated and illed with molten material during the course of itsmovement through said guide.

4. The apparatus according to claim 2 characterized further in that themold blocks preceding and following such passages have sealed, slidingengagement with said guide.

5. The apparatus according to claim l characterized further in that saidmold comprises an elongated rodlike member forming a longitudinallyextending passageway with said guide into which the molten material owsduring movement of said member through said guide.

6. Apparatus for casting articles comprising a mold having a cavity, aninert atmosphere chamber containing a receptacle for molten metal withrespect to which said mold is adapted to be moved to successively exposethe cavity therein to such atmosphere and to communicate the cavity withmolten metal in said receptacle for iilling said cavity, an upwardlyextending guide connected to the upper part of said chamber whichembraces said mold and provides a seal against inflow of atmosphere intosuch chamber as said mold moves through said guide into said chamber,said receptacle being provided with a downwardly extending guideconnected to the lower part of said receptacle and aligned with saidupwardly extending guide for guiding movement of said mold downwardlyand for forming with said mold and metal therein a closure for saidreceptacle as said mold is thus moved, and means for cooling said moldprogressively upwardly from the bottom thereof and thus correspondinglysolidifying the metal therein and providing a shrinkhead of molten metalwhich compensates for shrinking of the metal below.

References Cited in the tile of this patent UNITED STATES PATENTS GreySept. 14, Grey Nov. 14, Moxham Apr. 29, Davenport Sept. 11, Sherwood etal. Dec. 18, Sherwood Apr. 23, Sendzimir Mar. 23, McCarroll et al. Sept.7, Thompson Dec. 20, Galloway Aug. 6, Smithson et al. Jan. 12,

6. APPARATUS FOR CASTING ARTICLES COMPRISING A MOLD HAVING A CAVITY, ANINERT ATMOSPHERE CHAMBER CONTAINING A RECEPTACLE FOR MOLTEN METAL WITHRESPECT TO WHICH SAID MOLD IS ADAPTED TO BE MOVED TO SUCESSIVELY EXPOSETHE CAVITY THEREIN TO SUCH ATMOSPHERE AND TO COMMUNICATE THE CAVITY WITHMOLTEN METAL IN SAID RECEPTACLE FOR FILLING SAID CAVITY, AN UPWARDLYEXTENDING GUIDE CONNECTED TO THE UPPER PART OF SAID CHAMBER WHICHEMBRACES SAID MOLD AND PRIVIDES A SEAL AGAINST INFLOW OF ATMOSPHERE INTOSUCH CHAMBER AS SAID MOLD MOVES THROUGH SAID GUIDE INTO SAID CHAMBER,SAID RECEPTACLE BEING PROVIDED WITH A DOWNWARDLY EXTENDING GUIDECONNECTED TO THE LOWER PART OF SAID RECEPTACLE AND ALIGNED WITH SAIDUPWARDLY EXTENDING GUIDE FOR GUIDING MOVEMENT OF SAID MOLD DOWNWARDLYAND FOR FORMING WITH SAID MOLD AND METAL THEREIN A CLOSURE FOR SAIDRECEPTACLE AS SAID MOLD IS THUS MOVED, AND MEANS FOR COOLING SAID MOLDPROGRESSIVELY UPWARDLY FROM THE BOTTOM THEREOF AND THUS CORRESPONDINGLYSOLIDIFYING THE METAL THEREIN AND PROVIDING A SHRINKHEAD OF MOLTEN METALWHICH COMPENSATES FOR SHRINKING OF THE METAL BELOW.